LAUSR

This work deals about the evaluation and improvement of analytical and electrochemical features of chemically modified electrode based on dihexadecyl hydrogen phosphate (DPH) and carbonaceous materials. The electrochemical features of films obtained were evaluated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Between the modifications evaluated, the glassy carbon electrode (GCE) modified with CB and DPH (DHP-CB/GCE) showed lower resistance to charge transfer and higher electron transfer rate. Additionally, the highest current of U(VI) was obtained with DHP-CB/GCE in a very stable way, the process present quasi-reversible behavior and it is controlled by a mixture of diffusion and absorption. The best instrumental conditions for U(VI) determination were obtained applying frequency of 15 Hz, amplitude of 100 mV, and deposition potential of − 0.1 V (by square wave cathodic stripping voltammetry). Among the electrolyte compositions (acetate and citrate buffers), ionic strength (from 0.10, 0.15, to 0.20 mol L −1 ), and pH (from 3.6 to 5.6) evaluated, the highest current of U(VI) were obtained in 0.15 mol L −1 of acetate buffer, pH 5.6. The method was accurate, linear, and sensitive (detection limit of 0.088 μg L −1 using 300 s of deposition).